Institute for Neurophysiology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
J Cereb Blood Flow Metab. 2013 Feb;33(2):263-71. doi: 10.1038/jcbfm.2012.165. Epub 2012 Nov 21.
The brain is an organ with high metabolic rate. However, little is known about energy utilization during different activity states of neuronal networks. We addressed this issue in area CA3 of hippocampal slice cultures under well-defined recording conditions using a 20% O(2) gas mixture. We combined recordings of local field potential and interstitial partial oxygen pressure (pO(2)) during three different activity states, namely fast network oscillations in the gamma-frequency band (30 to 100 Hz), spontaneous network activity and absence of spiking (action potentials). Oxygen consumption rates were determined by pO(2) depth profiles with high spatial resolution and a mathematical model that considers convective transport, diffusion, and activity-dependent consumption of oxygen. We show that: (1) Relative oxygen consumption rate during cholinergic gamma oscillations was 2.2-fold and 5.3-fold higher compared with spontaneous activity and absence of spiking, respectively. (2) Gamma oscillations were associated with a similar large decrease in pO(2) as observed previously with a 95% O(2) gas mixture. (3) Sufficient oxygenation during fast network oscillations in vivo is ensured by the calculated critical radius of 30 to 40 μm around a capillary. We conclude that the structural and biophysical features of brain tissue permit variations in local oxygen consumption by a factor of about five.
大脑是一个代谢率很高的器官。然而，对于神经元网络在不同活动状态下的能量利用情况，人们知之甚少。我们在海马切片培养的 CA3 区使用 20%的 O(2)混合气体，在明确的记录条件下解决了这个问题。我们在三种不同的活动状态下同时记录局部场电位和间质局部氧分压（pO(2)），这三种状态分别是：在伽马频段（30 到 100 赫兹）的快速网络振荡、自发网络活动和无尖峰活动（动作电位）。通过具有高空间分辨率的 pO(2)深度分布和考虑了对流传输、扩散和活动依赖性氧消耗的数学模型来确定耗氧率。我们的研究结果表明：（1）与自发活动和无尖峰活动相比，胆碱能伽马振荡期间的相对耗氧率分别高出 2.2 倍和 5.3 倍。（2）伽马振荡与先前用 95%O(2)混合气体观察到的情况类似，伴随着 pO(2)的显著下降。（3）通过计算得出，在毛细血管周围 30 到 40 微米的临界半径内，可以确保体内快速网络振荡期间有足够的氧合作用。我们得出结论，脑组织的结构和生物物理特性允许局部耗氧量在大约五倍的范围内变化。
